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Brain Morphology of Cannabis Users With or Without Psychosis: A Pilot MRI Study
Published on: August 18, 2020
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Cannabis use as a risk factor for causing motor vehicle crashes: a prospective study
Jeffrey R Brubacher1, Herbert Chan2, Shannon Erdelyi2
1Vancouver General Hospital and University of British Columbia, Vancouver, BC, Canada.
Addiction (Abingdon, England)
|May 21, 2019
Summary
Drivers with less than 5 ng/ml of Δ-9-tetrahydrocannabinol (THC) showed no increased crash risk. A non-significant increased risk of crash responsibility was observed in drivers with THC levels of 5 ng/ml or higher.
Area of Science:
- Forensic Toxicology
- Drug Safety
- Traffic Safety
Background:
- Motor vehicle collisions are a significant cause of injury and death.
- The role of Δ-9-tetrahydrocannabinol (THC) in driver impairment and crash responsibility is a critical public health concern.
- Understanding the association between THC levels and crash culpability is essential for developing effective safety policies.
Purpose of the Study:
- To determine if injured drivers testing positive for THC or other drugs are more likely to have contributed to a motor vehicle collision.
- To quantify the association between different blood THC concentrations and crash responsibility.
- To compare the crash risk associated with THC to that of alcohol and other impairing substances.
Main Methods:
- A prospective case-control study was conducted involving injured drivers requiring blood tests in British Columbia, Canada.
- Excess whole blood was analyzed for alcohol, THC, and other impairing drugs/medications.
- Police crash reports were reviewed to determine driver responsibility, with logistic regression used to calculate odds ratios adjusted for confounders.
Main Results:
- Of 2318 drivers with police reports, 8.3% tested positive for THC.
- No increased crash risk was found for drivers with THC levels < 5 ng/ml.
- Drivers with blood alcohol concentration ≥ 0.08%, other recreational drugs, or sedating medications showed significantly increased crash responsibility.
Conclusions:
- In this cohort, THC levels < 5 ng/ml were not associated with increased crash risk.
- A statistically non-significant increased risk of crash responsibility (OR=1.74) was observed for drivers with THC ≥ 5 ng/ml.
- Alcohol and other recreational/sedating drugs demonstrated a significant association with crash responsibility.
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